Purpose: :
Anisometropia was recently shown to develop in ten percent of infants diagnosed with nasolacrimal duct obstruction at a mean age of one year. The purpose of this study is to determine whether earlier (< 1 year) spontaneous resolution or probing decreases or eliminates this risk.

Methods: :
The medical records of all patients diagnosed as an infant with CNLDO from January 1, 1988, through December 31, 1992, and who later underwent a refraction were retrospectively reviewed. Anisometropia was defined as ≥ 1 diopter of refractive error between the two eyes.

Results: :
A total of 560 infants were diagnosed with CNLDO during the 5-year period, of which 258 (46.1%) subsequently underwent a complete ophthalmic examination. Of the 258, 195 (75.6 %) spontaneously resolved at a mean age of 4.5 months (range, 0.3-35 months), 61 (23.6 %) were managed with probing at a mean age of 19.7 months (range, 0.5-100 months), and the remaining 2 had persistent tearing without treatment. Anisometropia developed in 21 (10.8 %) of the 195 who spontaneously resolved and in 4 (6.6 %) of the 61 operated children (p=0.33). Among those who underwent surgery, there was no significant difference (p=0.70) in the rate of anisometropia between those treated at less than (n=25), compared to greater than, one year of age (n=36).

Conclusions: :
Early spontaneous resolution of CNLDO is not associated with a lower subsequent risk of developing anisometropia. It is unclear, however, due to small numbers, whether or not early probing can modify or eliminate this risk.